Rectifying system



Mam 22, 1932.

J. E. FOSTER RECTIFYING SYSTEM Original Filed Jan. 8, 1925 INVENTORPatented Mar. 22, 1932 UNITED STATES PATENT OFFICE JULIUS. a; FOSTER, orPITTSBURGH, PENNSYLVANIA, ASSIGNOR To :aAmo CORPORATION or AMERICA,CORPORATION or DELAWARE REcTmYrNG SYSTEM Original application filedJanuary 8, 1925, SerialNo. 1,182. Divided and this application. filedMarch 5,

1929, Serial No. 344,336.

This application is adivision of myapplicaton relating to thermionicdevices filed Jan. 8, 1925, Ser. No. 1,182, and is directed particularlyto a rectifying system, including thermionic devices.

The primary object of my invention is to provide a rectifying systememploying a fullwave thermionic rectifier provided with a plurality ofthermionic cathode elements and 9 co-operating anode means arranged toprevent current leakage between the cathode elements, and, thereby, toprevent short-circuiting of a transformer or other source of energy withwhich the rectifier may be employed.

Another object of my invention is to provide a rectifying system forradio application, which shall transmit substantially all;

of the rectified energy, and thereby maintain a substantially constantsource of direct voltage.

Another object of my invention is to provide a rectifying system, of theforegoing character, that may be utilized in radio I equipment with atransformer that supplies voltage of desired value, and that shallfunction in such manner as to protect the transformer againstshort-circuit conditions caused tween two cathodes, or the actlve spacessurrounding them, the anode means should be by current leakage betweenthe filaments of a double wave rectifier.

' Recent developments in radio receiving equipment have been towards theelimination of the various storage and dry batteries heretofore used, inorder that the usually available source of house-lighting current mightbe utilized for the energization of radio tubes and the operation of thereceiving sets. In order to obtain a suitable supply of substantiallydirect current and direct current voltage, rectifying devices ofdifferent kinds have been employed, utilizing the thermionic valvecharacter of a heated cathode. With the employment of two heatedcathodes in the same envelope, however, for transmitting both waves ofan alternating current, certain problems are encountered which must beeliminated in order to obtain satisfactory operation of the rectifier ofsuch type.

Where two filamentary electrodes disposed in the same enclosing Vesselare heated, the spaces or zones immediately surrounding Renewed July 11,1931.

the filaments become electronically active due to alternately transmitcurrent waves to the anode element, the differences of potential set-upbetween the various elements, in the confined space within the envelope,tend to establish greater activity between the several electronic spacessurrounding the active cathodes, and a short circuit condition isestablished on the transformer to which the rectifier is connected.

If both filaments are to be disposed within the same envelope, as ispreferable for reasons of economy and for saving of space, it isessential to prevent the leakage of current between the two filaments,or proper operation of the rectifying system will not be established andmaintained, and a short-circuit condition will be established by suchleakage.

In order to prevent current leakage bedisposed to isolate and confinethe active spaces surrounding the respective cathodes,

and thereby prevent leakage of current be tween the cathodes or theactive spaces surrounding them, and thus prevent the possibility of ashort circuit upon the transformer or source of alternating current withwhich the rectifier is to be used.

In the modification which is illustrated herein, the cathode filamentsare isolated and separated from each other by a common anode which isprovided with a partition to divide the anode into two chamberenclosures. A filamentary cathode is disposed in each chamber. Theactive space surrounding each filament is thus confined and limited andisolated by the chamber enclosure wall, and the potential of the anodepartition is such as to permit the passage of current in a properdirection between the anode and one filament or the other, dependingupon the potential of the circuit or transformer to which the rectifieris connected. At the same time, current transfer between the filamentsis prevented and the transformer is protected against short-circuitconditions.

The operation of the rectifying system will be better understood uponreference to the following detailed description in consideration withthe accompanying drawings, in which Fig. 1 illustrates schematically a3-element tube with a single wave rectifier system for excitationof thecathode;

Fig. 2 illustrates schematically a similar system to that shown in Fig.1 but arranged to supply double-wave rectification;

Fig. 3 is a schematic and diagrammatic View of a tube and system similarto that shown in Fig. 2 but employing an anode of special constructionfor the rectifying operation- Fig. 4 is a perspective view of the commonanode used in the rectifying operation in the tube shown in Fig. 2;

Fig. 5 is a sectional view of the anode of modified constructionemployed in the tube shown in Fig. 3;

Fig. 6 is a perspective view of the same anode illustrating the mannerin which the partition separates the anode into two chambers forreceiving the cathodes;

Fig. 7 is a front elevational view of a tube embodying the featuresillustrated in Fig. 3;

Fig. 8 is a front view, partially in elevation and partially in section,of the tube shown in Fig. 7

Fig. 9 is a sectional View of the tube shown in Fig. 8, taken alongthe-line IX-IX, together with the connected circuits.

The tube illustrated in Fig. 1 comprises a vessel 10 divided into twocompartments, an operating compartment and a rectifying compartment, bya partition 11 consisting of a glass annulus 12 and a tungsten disc orplate 13 supported in the center thereof. One compartment contains agrid 14 and a plate 15. The other or rectifying compartment, contains afilament .16 and some inert gas such as argon. The filament 16 isenergized from v an alternating current circuit 18 through a transformer19 which is also connected through a resistor 21 to include therectifying chamber in a series circuit. The filament is thereby renderedincandescent and the target or plate 13 is heated by bombardment and bythe current traversing it. The plate 13 should have an oxide coating onthe surface in the operating compartment but not on the surface in therectifying compartment. The plate will thus be rendered active at atemperature considerably lower than the operating temperature of thefilament. There will therefore be lessactivity and electron emissionfrom the uncoated surface of the plate than from the filament. Therectifying character of the filament and the plate will therefore not beaffected inasmuch as the potential diiference between them will beinsuificient to cause a reversal of current and a penetration of thehighly active electron field near the filament. The striking potentialnecessary to cause a reversal would be of the order of to 200 volts forabout inch spacing. The voltage necessary to operate the rectifyingcompartment need only be somewhat in excess of the initial strikingpotential which would be about 25 to 30 volts for the same spacing. Theoperation is similar to that of the tungar battery charging rectifier.

In Fig. 2 is illustrated a modification which utilizes all current wavesof both polarities, thereby supplying a continuous unidirectionalcurrent to the plate oranode 22, and maintaining the temperature moreeven. Two rectifying compartments are provided, which are partitionedfrom the main compartment and each other. The plate 22 embodies twoportions 23 and 24 respectively disposed in partitions 11 and 26separating the several compartments. Two filaments 16 and 16a in therectifying compartments transmit current alternately to the plate 22.

which is consequently energized continuously by uni-directional current.The value of the current transmitted may be controlled by the variableresistor 21, and the temperature and electron-emitting character of thesurface of the plate in the main compartment varied accordingly.

The filaments are heated by separate auxi1 iary low-voltage windings 28and 29 of the transformer. The anode 22 is connected to the neutralpoint 30 of the main transformer Winding 31, and the auxiliary windingsare connected to points on either side of the neutral 30, according tothe voltage that is to be impressed upon the rectifier.

In Fig. 3 is illustrated a modification embodying an anode 33 of coneshape, which is energized in accordance with the principle controllingthe tube in Fig. 2. The anode cone 33 is divided into'two pockets orchambers by a partition 34. of corresponding metal. Each pocketcommunicates withthe corresponding rectifying compartment andconstitutes part thereof. The filaments are sup-.

by a. continuous uni-directional curpartition 34 in the cone-shapedanode33 and in the auxiliary partition 26 between the rectifying chambers. Bymeans of the partition 34 in the cone and the glass partition 26, the

two chambers are entirely separated.

In Figs. 7 8, and!) are shown the embodiment containing the featuresillustrated in Fig. 3. The view in Fig. 7 shows the disposition of thecone 33 as a cathode within a plate 36 of truncated cone shape. Thepartition 34 in the cone is anchored in a glass partition 26 across thetube underneath the cone and its supporting annulus 25.

The view in Fig. 8 is a side sectional view of the tube in Fig. 7 withparts broken away to show the disposition of the various elements. Thecone is surrounded by a grid 37 within theplate 36 and is supported by aconductor proceeding to one of the base terminals. The rectifyingfilaments 16 and 16a are disposed within the pockets in the cone, oneach side of the partition 34. The filament supports are sealed in theusual reentrant stem or press, and connected to base termimale. The apexof the cone is also connected to a base terminal through a conductor andsupport.

By disposing the rectifying filaments within the cone, all heatdeveloped thereby is pocketed and confined to establish a heat zone tomaintain the temperature of the cone substantially constant.

The view in Fig. 9 is a sectional view of the tube in Fig. 8 taken alongthe line IX-IX n the direction of the arrows. The vertical glasspartition 26 co-operates with the cone partition to separate therectifying compartments. to those illustrated in Fig. 3.

By means of the cone structure illustrated in the described figures, aneven constant temperature may be maintained, due to the heat storagecapacity of the cone and to the fact that the heated air is pocketed inthe "one. The outer surface of the cone may be coated with commercialoxides as at present employed to obtain high electron emission atrelatively low temperatures. The heating and temperature of the. conemay be con- "rolled by the rtsistor 21 in the energizing circuit. Bymeans of such a system a. re.atively large heating current may besupplied to the cone. which permits of greater flexibility andregulation. controlling the "urrent traversing the rectifying filamentsand also the current traversing the filamentcone circuit, the operatingcharacteristics of the cone in the operating compartment may be readilycontrolled.

It is essential for proper operation of the The circuit connectionscorrespond rectifying units that the filaments be separated to obviate aclear path between them which would permit a partial short circuit andconsequent erratic operation resulting in a fluctuating energizingcurrent. Such erratic operation results when both filaments have anunimpeded gas path between them. By. means of the glass partitionandthat in the cone, a transfer of energy between the filaments isprevented and all energy transmitted to the cone.

In order to ensure proper operation of the rectifying unit the twofilaments and their active spaces should be confined in separatecompartments, to preclude leakage or shortcircuit currents between them.

My invention is not limited to the specific arrangement and constructionthat is illustrated but may be variously modified to employ the sameprinciple of separating and segregating or isolating the active zonesaround the respective cathodes to prevent inter-electronic action orcurrent leakage between them that would be detrimental to and wouldshort circuit the associated transformer, all as are set forth as beingwithin the spirit and scope of the invention as defined in the appendedclaims.

I claim as my invention:

1. The combination in a rectifying system,

comprising a transformer, a source of energytherefor, a rectifierprovided with two filamentary electrodes energized from the transformer, anode means associated with the filaments and means conductiveto direct current between the transformer and the filaments and theanode means to transmit alternate waves from the filaments, said anodemeans being disposed around the active zones of the filaments to preventcurrent leakage between them and consequent short-circuiting of thetransformer.

2. In a radio system, the combination with a transformer, of athermionic tube comprising an audion and a full-wave rectifier havingheatable cathodes and a common anode which is the cathode for theaudion, means energized from the transformer for heating the cathodes,and means conductive to direct current connecting the transformer, thecathodes and the anode in a rectifying circuit, the anode having abarrier isolating the active spaces surrounding the cathodes to preventcurrent leakage between them which would short-circuit .the transformer.

3. In a radio system, the combination with a transformer, of a full-waverectifier having heatable cathodes and anode means, means energized fromthe transformer for heating the cathodes,'and means for conductingdirect current connecting the transformer and the cathodes and anodemeans in a rectifying circuit, said anode means isolating the activespaces surrounding the cathodes to prevent current leakage between themand, thereby,

' to prevent consequent short-circuiting of the transformer.

4. In an electrical system, the combination with a transformer, of arectifier having a plurality of heatable cathodes, means ener-' gizedfrom the transformer for heating the cathodes, anode means associatedwith the cathodes, and means conductive to direct current connecting thetransformer, the cathodes and the anodes as a rectifying circuit,

ed to the transformer for causin the cathode elements alternately totransmit a current wave. said .means including anode means associatedwith the cathode elements and arranged to receive the current wavestherefrom, means conductive to direct current between the anode meansand the transformer, and an insulating medium cooperative with the anodemeans to isolate the active spaces surrounding each cathode element,thereby to prevent current leakage between the cathode elements andconsequent short-circuiting of the transformer.

6. A rectifying system comprising a transformer, a rectifier embodying aplurality of cathode elements and anode means associated therewith, andmeans .conductive to direct current connecting the cathode elements andthe anode means to. the transformer to cause current waves to betransmitted alternately between the respective cathode elements and theanode means, said anode means being disposed to isolate the activespaces surround- I ing the respective cathode elements, thereby toprevent current leakage between them and to prevent consequentshort-circuiting of the transformer.

7. In a rectifying system, the-combination with a transformer, of arectifier provided with two filamen ary cathodes, means ener- I gizedfrom the t ansformer'for energizing the cathodes, and means electricallyassociatng the cathodes and the transformer to cause the cathodes to bealternately efiective to transmit current waves, said means includinganode means comprising two chamber enclosures respectivelysurroundingand isolating the active spaces surrounding the cath odes,whereby leakage between the cathodes and consequent short-circuiting' ofthe transformer are prevented, and means conductive to direct currentconnecting the anode means and the transformer 8. A rectifying systemcomprising a transformer, a full-wave rectifier having heatable cathodesand co-operating anode means, a load circuit, and circuit connectionsconductive to direct current operatively connecting the transformer andthe cathodes and the anode means to supply double-wave rectified currentto the load circuit, said anode means surrounding and isolating theactive spaces surrounding the cathodes to receive the full current wavesfrom the cathodes for the load circutand, thereby, to prevent currentleakage between the cathodes and consequent short-circuiting of thetransformer.

9. In a rectifying system, the combination with a transformer, of athermionic rectifying device comprising two filamentary cathodes andco-operating anode means, means energizable from the transformer forheating the cathodes; an impedance device conductive to direct current,and means including the anode means electrically associating thetransformer and the cathodes to render the cathodes alternatelyeffective to transmit current waves to the anode means and the impedancedevice, said anode means isolating and surrounding the cathodes toprevent current leakage between them that would short-cir-.

cuit the transformer.

10. In a rectifying system, the combination comprising a thermionicdevice provided with two elements for establishing two spacedelectronically active zones, means for energizing said elements, andmeans for controlling said elements, when energized, to alternatelyestablish a current-carrying stream.

from each active zone to said means, and precluding any leakage orinterchange of current between said zones, said means and said elementsbeing electrically connected by direct current conductors externally ofsaid streams. Y

11. In a rectifying system, a thermionicof the rectifier.

12. In 'a rectifying system, a thermionic. rectifier provided with aplurality of filamentary cathodes, means for energizing them to renderthem electronically active, co-

operating anode means disposed around and 7 between the cathodes totransmit current waves to the respective cathodes and to pre ventcurrent. leakage between them due to their electronic activity, a sourceof energy therefor andmeans electrically conductive to direct currentconnecting the cathodes and to prevent current leakage between them, 7

and means electrically conductive to direct current connecting thecathodes and the collectin means externally of the rectifier.

14. 11 an electrical system, the combination comprising a singlephase'transformer, a rectifier having two spaced'heatable cathodes,means energizable from the transformer for heating the cathodes toestablish two spaced active zones, anode means associated with thecathodes, means conductive to direct current connecting the transformer,the

= cathodes'and the anode means as a rectifying circuit and setting upthe full transformer voltage between said zones, the anode meansembodying a conducting barrier disposed directly between the two spacedactive zones, and an insulating medium co-operative with the conductinganode barrierto separate the spaced active zones and to prevent energyinterchange between-them in response to the transformer voltage betweenthe two active zones, and, thereby, to prevent consequentshort-circuiting of the transformer.

15; In a rectifying system, the combination'comprising a single phasetransformer, a rectifier having two spacedheatable cathodes, effective,when heated, to establish two spaced active zones, means energizablefrom. the transformer for heating the cathodes,

anode means associated with the cathodes,

and means conductive to direct current connectmg the transformer, thecathodes and the anode means as a rectifylng circuitand introducing thepotential of each terminal of the transformer into the respective actlvezones, said anode "means embodying a conducting barrier disposeddirectly between the two'spaced active zones and establishing apotential and an effective reaction upon -the energy of the two zonesaccording to the changing potential-of the transformer terminals and aninsulating medium, ina path beyond the conducting barrier and between'the active zones, co-operative with the anode barrier to separate thespaced active zones and to prevent energy interchange between them inresponse to the potent al difference established between-the two zonesby the transformer voltage, and, thereby to prevent consequentshort-circuiting of the trans-' former. v In testimony whereof, I havehereunto subscribed my name this 2nd day of March, 1929,

' JULIUS E. FOSTER. j

